The Icon's only weak spot was the opening on the forehead exposing its brain. Once the cube would make contact with a rough surface, the demon is summoned. By doing so, it would launch a cube with skull faces engraved onto each side. As for its capabilities, it had the power to summon demons of all types minus Cyberdemons and Spider Masterminds. The creature itself had no display of emotion during its encounter with Doomguy. Its death results in the closing of the second Hell Portal and the demonic forces falling into disarray. Using whatever weapons he could salvage, Doomguy shoots the Icon's opened forehead and destroys it. Upon arrival, he had slain countless demons while making his way to the Icon's chamber. Once the USMC had received an intelligence report about what was leading Hell's army, Doomguy intercepted the Icon by travelling back to Hell.

It was the Icon of Sin that made contact with the Hell Portal buried in the middle of Doomguy's hometown on Earth. Most of the survivors of the First Demonic War would confuse the Icon as Satan given its unique powers and ability to lead. What is known about it is that it was one of the most powerful beings of Hell and was responsible for the hellish monsters that attacked the Mars expedition and Earth. There is very little information about the Icon of Sin and its origins. The modder for DOOM: Reawakened disliked the Icon of Sin and decided to not include one in the mod. It is rumored that it had a gigantic body behind that wall. The Icon of Sin is depicted as a giant goat-like demon head bio-mechanically mounted into a wall. As it is not the so-called average monster, it does not count as a monster kill once defeated. The NPC hidden inside the Icon has a sprite of a severed head resembling John Romero. Instead, id Software created wall textures serving as the Icon's face while the actual enemy NPC was hidden behind them. In DOOM II: Hell on Earth, the Icon of Sin is not an actual monster NPC like all of the other demonic variants.

Doom eternal icon of sin